Braking apparatus



June 25, 1935. s. 5c NE 2,005,874

BRAKING APPARATUS Filed Feb. 26, 1932 2 Sheets-Sheet l W WW - Inventor 7 V STEVE SCHNELL Att'y.

June 25, 5 SCHNELL BRAKING APPARATUS Filed Feb. 26. 1932 2 Sheets-Sheet 2 -TEVE SCHNELL Atty.

Patented June 25, 1935 PATENT OFFICE BRAKING APPARATUS Steve Schnell, St. Louis, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corpora- 3 tion of Delaware Application February 26, 1932, Serial No. 595,259

50lalms.

My invention relates to braking apparatus and particularly to expanding brakes of the band type, its principal object being to provide a brake of this type so constructed as to aflord improved 5 and more uniform distribution of shoe pressure and thus secure better braking efllciency.

more uniform lining wear, and less tendency to produce squeaks during brake application.

Other objects and advantages of my invention will become apparent from the following description taken in connection with the accompanying drawings in which Figure 1 is a side elevation of a preferred embodiment of my invention; Figure 2 is a bottom view of my improved brake band; Figure 3 is a cross sectional view of the band on the lines 3-3 of Figure 1; Figure 4 is a cross sectional view on the line 4-4 of Figure 1; Figure 5 is a side elevation of a modified form of brake band; Figure 6 is a cross sectional view of the band on the line 6 6 of Figure 5; and Figure 7 is a side elevation of another modified form of brake band.

Referring to Figures 1 to'4 inclusive; numeral I indicates the drum of the brake which is se- 25 cured in the usual manner to the wheel of the vehicle and is enclosed on its open side by the backing plate or support 2 (Figure 4) secured to some fixed part of the vehicle. The brake shoe 3 is of the band type and is mounted within the 30 drum and adapted to have its free ends expanded into engagement with the drum by suitable means, such as the hydraulic mechanism 4. The band is biased to o position by the usual spring 5, its. ofif position clearance being determined 35 by the adjustable stops 6. The brake band disclosed, is of the'T-section type, comprising a lining carry-flange I and an integral web 8.

In'band brakes of uniform cross section and provided with an anchor located approximately 40 at the center of the band, it is well known that when the drum is rotating and the band is engaged with the drum there will be greater pressure between the band and the drum at some points than at others. For instance, if the drum is rotating in the direction of the arrow (Figure 1) the greatest pressure will occur at the central part of the shoe and the minimum pressure at a point approximately 60 degrees to the rear thereof. The maximum pressure at the central part of the band is due to the wrapping effect and the uneven bending movement of the band when applied to the drum, and the relatively low pressure at the 60 degree position mentioned, results from the reaction of the wrapping effect on this portion of the band tending to separate it from the drum, and to the fact that the revolving drum produces the reverse of a wrapping eflect at this point. The pressure at the point just referred to can be increased by the use of a combined anchor and radial pressure produc- 5 ing device of the type, for example, which is disclosed in the application of Steve Schnell, Serial No. 541,355. This device, indicated at 9, comprises a plate member l0 spacedfrom the backing plate by spacers II and secured thereto by 1 suitable means, such as rivets. A pair of plates l2 (one only being shown in Figure 1) are secured to the sides of the web 8 of the band between which the plate Ill extends. The outer edge of the plate 10 is provided with an inclined surface l3 which cooperates through a roller M with approximately parallel surfaces IS on the plates l2. It is thus seen that when the band is engaged with the drum it has slight circumferential movement therewith which causes the inclined surfaces l3 and I 5 to cooperate through the roller l4 to. produce an outward radial pressure on the band to force it into tighter contact with the drum. A tension spring I! maintains the roller in contact with the inclined surfaces. I

The placing of the combined anchor and radial pressure applying device at the point shown, increases the maximum pressure on the band near the central portion due to increase of the wrap ping effect resulting from increased distance from the "forward end of the band to the anchor. This condition is undesirable since it tends to distort the drum and to produce brake friction noise (squeaks) and causes rapid lining wear. To decrease this pressure, I propose to increase the flexibility of the band at this point, which may be accomplished, for example, by cutting away a portion of the flange l on each side of the web 8, as shown in Figures 2 and 3. The amount of flange to be cut away of course, dependent upon the character of the band material and the degree of flexibility desired.

The increasing of the flexibility of the brake band at the central part results in a marked advantage in the action of the brake as a whole. It not only reduces the pressure at this point, but decreases the bending or distortion force necessary to initially engage the ends of the band with the drum by means of the actuating mech- 6o anism and gives the brake band an approximation of the action of the two-shoe hinged type of brake in this respect. As shown, the lining It may be entirely eliminated at the cut away portion of the flange, thereby saving a considerable m m w aw MW mw mmwmmm mmwmw m Wm m E m x m m m mm m w m mmmd mgmmmmim. m mmdw m.m mmmmmmm m mmm mmmmmmmmwm mew mmm m m m mm mmmmfimmmm mmmmmm m mmmm m i mmm m mm m mflwmm m ww WWW? m m m r w mmc mmdm mm m mm m mummmv mmn m wmmm mwm mmm mmmmmMWWW mmmmm m m am a m m mm wiwm m mw mmm mmmwmfi m mmmm mm mmm m e w m u w limi ed w p I l forth y the pended portionotthebandwhichliesintermediatethe claims. forward end thereof and the combined anchor 'lheteaturehereindiacloeedofhavlnstfleandradi'aipremn'eproducingmeansandwhere lectedarcorarcsotthelminxcflrylnzflanee duringapplicationotthebrakethepressurebe- 86 ofam "m m tweenthebandandthedrumwouldbethesreotthereintorcingwehishroadlyclaimedinmyooegtflthennlngwereconflnm, 9 11111118 pp ti n Serial N 595,360- 5. In braking apparatus, the combination of a flavinznfllydeacribedmyinventiomwhatl rotatahlebrckedrummmhstanticllymdetree l0 claimasnewanddesiretoeecurebyletterahtflgxjblebmmdm'tomte mere- 0 entottbeUni edB lli with,mea.nstor appiyingthetree'endsotthe Llnbrakinaam hmt e bandtothedrum,nnchormeanslocatedatc rotatable brake drum, 8 flexible brake band pointmmthm lwmfmtheformd p to cooperate therewith. 830 m endoithehand,saidbandhnvingits flexibility I tortheband intermediate the ends thereoiLbrake incMpvu-thgt portion whichllu intermelinin: secured to the band, and means for ID- diatethei'orwardendotthehcndandthecnchor plyinzthebmdtothedrumJsidbrakobl-n andwheredm'inzapplicctionotthehrakethe b inzfr oflininaoverthctportionoithe -nd premirebetweenthebandmdthedrumwomd torwardottheanchormeanswhereduringbrake b the t tittb bm t t m. application the pressure betweenthebandand biiity,andhrakelininsecuredtoaaidbcndex 5 thedrumwouldbethegrettestitthelininzwere ceptomtheflexlbleportlon. continuum.

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